This invention relates, in general, to semiconductor packages, and more particularly, to a semiconductor package having internally molded isolation.
Some semiconductor packages which are required to dissipate a considerable amount of heat have an exposed heatsink area. Typically, a semiconductor device is mounted on a flag area of a leadframe. The flag area also serves as a heatsink which is partially exposed. However, some semiconductor circuits enclosed in such packages need to be electrically isolated from the heatsink. In some cases where it was necessary to electrically isolate the semiconductor device from any exposed heatsink portion the entire flag area which included the heatsink portion was encapsulated to ensure electrical isolation of the flag area. This resulted in the overall package being larger in size than a standard package and required careful control of the thickness of the encapsulating material around the heatsink portion in order to continue to maintain sufficient thermal conductivity between the heatsink and an external heat exchanger. Another approach to providing the electrical isolation was to make the heatsink separate from the flag area and then place an insulator, such as ceramic, between the flag area and the heatsink. The overall structure was then encapsulated leaving a portion of the heatsink exposed for mounting to a heat exchanger. However, this arrangement is difficult to assemble.
Accordingly, it is an object of the present invention to provide an improved semiconductor package having internally molded isolation.
Another object of the present invention is to provide an internally isolated semiconductor package made by a two stage molding process.
Yet another object of the present invention is to provide a semiconductor package having internally molded isolation with exactly the same external package dimensions as a standard package.